The development of high-speed storage devices, such as a SSD (Solid State Drive), a flash drive, and so forth, has made progress in recent years. A configuration for mounting a high-speed device in addition to a HDD (Hard Disk Drive), such as a SATA (Serial-ATA) disk and a SAS (Serial Attached SCSI) disk, is becoming widespread in storage systems. Device development will proceed ahead in the future as well, and the processing performance per device is on the rise.
For example, in a case where an extremely high-speed device like a flash drive is mounted in a storage system, there is the likelihood that the CPU processing performance in a single storage system will not be able to keep up with the processing performance of the flash drive, resulting in the storage system CPU performance becoming a bottleneck and making it impossible to fully utilize the flash drive resource. The high-speed device is generally more expensive than the HDD, raising a problem from the operating costs standpoint when it is not possible to make full use of the resource.
PTL 1 discloses a technology for alternating a volume, which is managed between disk control apparatuses, in accordance with the load on a disk control apparatus in a configuration that couples a plurality of disk control apparatuses to a plurality of disk drive apparatuses using either a network or a switch.